Photographic material

ABSTRACT

IMPROVED HEATED DRUM DRYING PROPERTIES ARE OBTAINED FOR PHOTOGRAPHIC SLVER HALIDE-GELATIN EMULSIONS WHEREIN SOME OF THE GELATIN IS MODIFIED TO KEEP IT FROM BEING HARDENED BY ORGANIC HARDENERS.

Claims priority, application Germany, Apr.

3,782,955 Patented Jan. I, 1974 United States Patent 3,782,955 i PHOTOGRAPHIC MATERIAL Bruno Mucke, Cologne, Karl Lohmer, Leverkusen, and Wolfgang Himmelmann, Opladen, Germany, asslgnors to Agfa-Gevaert Aktiengesellschaft, Leverkusen, Germany No Drawing. Filed Mar. 23, 19 71, Ser. No. 117211396731) P 20 18 552.8; July 4, 1970, P 20 33 26413 Int. Cl. (30% 7/00; G03c 1/72 US. Cl. 96-1143 5 Claims Improved heated drum drying properties are obtained for photographic silver halide-gelatin emulsions wherein some of the gelatin is modified to keep it from being hardened by organic hardeners.

ABSTRACT OF THE DISCLOSURE If the pictures are dried with their rear support surface.

in contact with the heated metal surface, a picture surface with a natural gloss of the silver halide-gelatin layer is obtained. Although the natural surface does not show a matt appearance in the true sense of the word the latter kind of drying is called matt drying.

High gloss drying and matt drying make very different demands on the photographic layer. In order to obtain a high gloss of good quality, the photographic layer must swell readily on heating so that it makes complete contact with the metal surface. For matt drying, on the other hand, that layer should not stick to the drying cloth by which the supported emulsion is pressed against the drum, in order to avoid contamination of the surface of the dried photographic layer with fibres of the. cloth. The

sticking of cloth fibres in the course of matt drying can be prevented by strongly hardening the outermost photographic layer. Under such. hardening conditions, however,

high gloss drying cannot produce a sufliciently smooth surface. i

i It is among the objects of the present invention to prometal drums. I

We now have found that such layers are provided by a gelatine silver halide emulsion in which 20 to 90% by weight of the gelatin consists 'of gelatin derivatives which cannot be hardened with organic hardeners. Such silver halide-gelatin layers can be covered by an outermost protective layer, the binding agent of which consists of hardened gelatin or of the gelatin derivative which cannot be hardened with organic hardeners or of mixtures thereof. Under gelatin derivatives which cannot be hardened with organic hardeners are reaction products of gelatin in which a high proportion of the hydroxyl and amino groups are blocked by acylation or in which the amino groups have been removed, e.g. by reaction with nitrous acid, and which can no longer be hardened by the addition of 0.5 of formaldehyde to produce layers which are fast to boiling. In the production of the non-hardenable gelatin derivatives, thedegree of gelatin conversion can be varied within wide limits by adding different quantities of acylating agents such as acid chlorides, acid anhydrides, sulfochlorides and isocyanates. A gelatin which has been acylated to an extent of 5% with acetic acid anhydride, for example, is a gelatin derivative which can still be hardened to produce layers which are fast to boiling by the addition of 0.5% of formalin. If the degree of acylation is increased to about 10%, a gelatin derivative is obtained which is no longer so hardenable.

In gelatin derivatives which are no longer hardenable, the number of free amino groups which are neither acylated nor substituted in some other way is very small. The free amino groups can be determined by Van Slykes method of nitrogen determination. In the gelatin derivatives that are no longer hardenable used the Van Slyke nitrogen value is below 0.3% (natural, untreated gelatin has a Van Slyke nitrogen value of 0.56%). j

The silver halide gelatin emulsion layer in which 20 to by weight of non-hardenable gelatin derivatives can be easily prepared by mixing ordinary, untreated photographic gelatin with the non-hardenable gelatin derivatives.

If a protective layer is arranged on top of the silver halide gelatin emulsion layer as mentioned above, and the protective layer contains gelatin as binding agent, that gelatin is hardened with an excess of organic hardener. Suitable .for use as hardeners are any known organic hardeners (aldehydes, acid halides, epoxides, ketenes). Alkoxy dichlorotriazines, formalin and the like are particularly suitable.

The photographic material of the present invention is suitable for high gloss drying as well as matt drying. Thus the contradictory requirements of both types of drying can be met with one and the same photographic material.

Non-hardenable gelatin modifications can be made by acylating gelatin with acid chlorides, acid anhydrides or sulfochlorides, or by reacting the gelatin with isocyanates, or by diazotization to convert its basis amino groups to hydroxyls. The production of some non-hardenable gelatin derivatives which are suitable for the present purpose has been described in US. Pats. Nos. 2,614,928 and 2,768,079. The acylation of some gelatin derivatives which may be used according to the invention is described in detail below.

COMPOUND I; ,ACETYL GELATIN 50 g. of gelatin are dissolved in 125 cc. of water at 40 C. and added dropwise to a solution of 7.5 g. of acetic anhydride in 25 cc. of anhydrous acetone in the course of 15 minutes. The pH is maintained at 8. The reaction mixture is stirred for a further 10 minutes and is then adjusted to pH 7 with sulfuric acid. The mixture is solidified and the resulting gel is noodled and rinsed in water for 2 hours. Van Slyke nitrogen content: 008%.

On the addition to the rinsed gel in layer form of 1% by weight of formaldehyde (based on gelatin) as a 30% aqueous solution, a melting point of the layer of 51 C. is obtained after 24 hours storage at 22 C.

COMPOUND II: ACETYL GELATIN 12.5 g. of acetic anhydride are added instead of 7.5 g. The method is otherwise the same as described under I. Nitrogen value according to Van Slyke: 0.06%.

On the addition to the acetylated material in layer form of 1% by weight of formaldehyde (in the form of a 30% aqueoussolution) based on the quantity of gelatin, the meltingpoint of the layer is 31? C. after 24 hours storage of the layers at room temperature.

COMPOUND III: PHTHALOYL GELATIN 60 g. of gelatin are dissolved in 1000 cc. of water, and 6 g. of phthalic acid anhydride dissolved in cc. of anhydrous acetone are added dropwise in the course of 15 minutes at 40. C. to .45? ,C. with stirring tion mixture is stirred for a further minutes and is then solidified and washed in water for 3 hours. The Van Slyke nitrogen value is 0.11%. I.

. After the addition to the phthaloyl gelatin in layer form of 1% by Weight of formaldehyde (based on gelatin) as a 30% aqueous solution, the melting point of the layers after 24 hours storage of the layers at 22C. is found to be C.

, COMPOUND IV: METHYL UREA GELATIN COMPOUND v; METHYL UREA GELATIENQ The procedure is the same as described for Compound IV except that 60 g. of methyl isocyanate are used. Van Slyke nitrogen value: 0.11%. A

After the addition of 1% by weight of formaldehyde (based on the total quantity of gelatin) as a aqueous solution, the melting point of the layers formed from the treated gelatin after the storage described above is 36 C.

COMPOUND VI: MALEINOYL GELATIN 200 g. of gelatin are dissolved in 1400 cc. of Water, and 30 g. of maleic acid anhydride dissolved in 120 cc. of acetone are added dropwise at C. to C. The pH is kept at 8 by the addition of sodium hydroxidesolution. The reaction mixture is then stirred for 15 minutes at C., the pH is then adjusted to 7 and the mixture is solidified and rinsed with water. Van Slyke nitrogen value: 0.15%.

If 1% by weight of formaldehyde (based on the total quantity of gelatin) is added in the form of 30% aqueous solution, the melting point of the layers obtained after casting, drying and 24 hours storage at 22 0.: of the treated gelatin, is 45 C. Y

COMPOUND VII: BENZOYL GELATIN 700 g. of gelatin are dissolved in 6300 cc. of Water, and a solution of 140 g. of benzoyl chloride in 250 cc. of acetone is slowly added dropwise at 40 C. At the same time the pH is kept at 9 to 10.with sodium hydroxide solution. The reaction mixture is stirred for 2 hours atpH 9 and 40 C., the pH is then adjusted to 7 and the mixture is filtered, solidified and rinsed with water for 4 hours. Van Slyke nitrogen value: 0.2%;

COMPOUND VIII: SUCCINOYL GELATIN 100 g. of gelatin are reacted with 15 g. of succinic acid anhydride dissolved in acetone and worked up in the same way as described in VII. A derivative which has a Van Slyke nitrogen value of 0.25% is obtained. The derivative cannot be hardened with organic hardeners,. or is only slightly hardened.

COMPOUND IX: DESAMINO GELATIN .f A

' 250 g. of gelatin are dispersed in a solution of 150 g. of sodium nitrite in 5 liters of water (temperature 22 C.). 70 cc. of glacial acetic acid are then added with stirring. The mixture has a pH of 4.1. It is stirred for about 2 hours at room temperature and the supernatant solution is then decanted off. The swelled particles of gelatin are then washed in water for 4 hours. After the last decanting, 10 liters of a 1% by weight aqueous sodium hyposulfite solution are added and the mixture is thoroughly stirred and left standing overnight. The supernatant'solu- The pH' i mainaiued a, 7,.,wi, h odiurnahvdroxider,solutienalhereact....

1 tion is decanted the gelatin left behind is digested .with.-a 0.L% byweight aqueous sodium hydroxide-solution and then treated successively with 0.3%, 0.2% and 0.1% aqueous acetic acid. The supernatant liquid is decanted off and water is added to the gelatin derivative which is then melted. Lastly, it is left to solidify, cast into small pieces and rinsed with water. i

. The addition of 1% by weight-of formaldehyde (based on the total quantity of gelatin) to the gelatin derivative in the form of a 30% aqueous solution shows that it can no longer be hardened.

In .general the silver halide of the emulsions of the present invention consist substantially of silver chloride or silver bromide with a silver iodide content of up to 4%.,by weight. p 1

Example 1 A silver bromide gelatin emulsion is prepared in'accordance with Fiat Final Report No. 354-360, page 28. This emulsion serves as comparison sample. A11 emulsion according to the present invention isprepared by basically the same method except that 85 by weight of the gelatin is replaced by Compound VIII.

The two emulsions were separately applied onto barytacoated paper support, the amount of silver applied being 1.5 g. of Ag/m. the form of silver halide;

A protective layer of ordinary untreated gelatin is then applied to the two emulsions from'a 2% gelatin solution. Thethickness of the protective layer is 3 microns. The layers were hardened With formaldehyde, the amount added to the silver halide emulsion being 1.5 ml. of a 30% formaldehyde solution per kg., and the amount added to the 2% protective-layer forming solution being 10. m1. of said formaldehyde solution per kg. To accelerate hardening of the layers, some samples of'the separately applied layers were stored for 48 hours in a heating cupboardat C. and 40% relative humidity.

All samples are processed in the same manner.-They are first exposed in a conventional sensitorneter behind a grey step wedge. The exposed material is developed in a developer of the. follow ing composition: p

1000 ml. of water 1 g. of p'-methylaminophenol 4g. of hydroquinone l3 g. ofjsodium sulfite cryst. 30 g. of potash v c 1 g'. of potassium bromide.v

The'development time is 90 seconds, the development temperatu're20 C. The material is then fixed and Washed in-the usualmanner.

'After washing, the samples are immediately subjected to mechanical ,high gloss andmatt drying. In all samples hardening is sufficient for matt drying and fibres from the cloth vdo not stick tothe surface. High gloss drying, on the other hand, produced an unacceptably large number of'surface faults in -thecomparison sample, whereas the high gloss in the material according to the present invention was excellent.

. "Thecomparison material also showed improved high gloss after it had been stored under natural conditionsfoi years,-,butthe number of surface faults in this material increased with age. After one year, the comparison material had. become unusable owing to the-excessively largenumber of surface faults, whereas the material according to the invention had an excellent high gloss after it had been completely hardened, and this gloss did not change with storage. I 1

Example '2 c pared form the same basic .as well as matt drying are obtained only with the material according to the invention. The comparison sample shows a satisfactory high gloss in the fresh state after it has been processed but it is not suitable for matt drying because residues of fibres stick to the surface of the layer. The capacity for matt drying improved in the course of storagevbu't the high gloss properties deteriorated to the same extent. The material according to the invention remained unchanged in its good high gloss and matt drying properties even after prolonged storage.

An additional advantage of the material according to the present invention is found in thestability of the image tone. Sensitometer strips of the material according to the invention showed a slightly warmer brownish image tone than the comparison sample even in the fresh state immediately after casting and drying of the emulsion layers. After storage in the heating cupboard and after storage under natural conditions over a period of one year, the comparison sample showed an undesirable shift in the image tone towards bluish black, whereas the material according to the invention retained its warm brown image tone.

Example 3 The procedure was the same as in the previous Example FIG. 1. The comparison emulsion was prepared according to Fiat Final Report No. 354-360, page 18. The emulsion prepared was a silver chloride gelatin emulsion. In the emulsion according to the invention, 30% of the gelatin in this recipe was replaced by Compound II.

The same results are obtained. The emulsion according to the present invention has excellent high gloss and matt drying properties, whereas the comparison emulsion is not satisfactory in this respect.

EXAMPLE 4 A silver chloride/bromide gelatin emulsion with a Warm brownish image tone is prepared in accordance with Fiat Final Report No. 354-360, page 33. This emulsion is used as control sample.

The emulsion according to the invention is based on the same recipe, except that 80% by weight of the gelatin is replaced by an equivalent quantity of Compound III.

Both emulsions are separately cast onto a baryta paper layer support. A 1.5 micron thick protective layer of Compound II is then applied to the emulsion layer containing modified gelatin.

An equally thick protective layer of untreated gelatin is used for the conventional silver bromide gelatin emulsion layer according to Fiat Final Report.

The samples are hardened with formaldehyde, 1.5 ml. of a 30% by weight formaldehyde solution per kg. being added to the silver halide emulsions, and ml. of a 30% by weight formaldehyde solution per kg. to the protective layers. To accelerate hardening, each sample was stored for 48 hours in a heating cabinet at 60 C./ 40% rel. humidity.

The two samples are processed in the same way. First of all they are exposed behind a grey step wedge in a conventional sensitometer. The exposed material is developed in a developer of the following composition:

1000 ml. of water 1 g. of p-methylaminophenol 4 g. of hydroquinone 13 g. of cryst. Sodium sulfite 30 g. of potash 1 g. of potassium bromide.

The developing time is seconds and the developing temperature 20 C. The samples are then fixed in the usual way and rinsed with water. 1

After rinsing, the samples are immediately subjected to machine high-gloss and matt-drying. In both samples,

the degree of hardening is sufiicient for matt drying, no

traces of fibre from the cloth adhere. By contrast, high gloss drying showed that the comparison sample has an unacceptable number of surface defects or faults, whilst in the case of the material according to the invention the high gloss is outstanding.

After natural storage for 3 months, the comparison material also showed improved high gloss. The number of surface faults in this material, however, increased with its age. After one year, the comparison material was unusable due to the excessive number of surface defects, whilst the material according to the invention showed outstanding high gloss which did not change with storage.

The material according to the invention is further distinguished by the outstanding stability of the warm brown image tone both during matt drying and also during high gloss drying. In the conventional material, without the gelatin derivative in the silver halide emulsion layer or the protective layer, the image tone is displaced to blueblack.

Example 5 The same emulsion samples as in Example 4 were prepared. A protective layer of Compound VII is applied in a thickness of 1.5 microns to the silver halide emulsion layer modified with the gelatin derivative. The conventional comparison emulsion receives a protective layer of pure gelatin.

Processing is carried out as in Example 1.

After storage for about 2 weeks, the material according to the invention can be subjected to machine matt-drying and high-gloss-drying. By contrast, the comparison material is unsuitable for matt drying even after this brief period of storage, because numerous fibres from the cloth remain adhering to the layer.

Example 6 The same emulsion samples as in Example 4 were prepared. A 1.5 micron-thick protective layer of 50% by weight of Compound III and 50% by weight of untreated gelatin, is applied to the silver halide emulsion layer with the modified gelatin. The conventional com parison emulsion receives an equally thick protective layer of pure gelatin. Processing is carried out as in Example 1. After 3 months, 6 months and 1 year, the material was tested for machine high gloss and matt drying and for image-tone stability. Whereas in the case of the comparison material the number of surface faults in high-gloss drying increased with increasing age and the warm tone of the fresh material became increasingly more blue-black in color as hardening increased during storage, and high-gloss quality and warm image tone of the material according to the invention did not undergo any changes during storage.

Similar results are obtained when replacing Compound III by other gelatin derivatives.

What is claimed is:

1. A light-sensitive photographic material of improved drying properties comprising a support and at least two layers forming a light-sensitive material supported on the support, and in superimposed, contacting relationship, said light-sensitive material consisting of an outer layer of gelatin hardenable by formaldehyde treatment, said hardening results from reaction of the gelatin with the formaldehyde and beneath said outer layer a light-sensitive photographic silver halide gelatin emulsion in which 20-90% of the total gelatin has been modified to have a Van Slyke nitrogen content less than 0.3% adjacent to the support so that the layer closer to the support is not hardenable by formaldehyde and is a support for the outer hardened layer.

'2. The light-sensitive photographic material of claim 1 wherein the modified gelatin is gelatin that has been acylated or reacted with an isocyanate or in which its basic amino groups have been converted to hydroxyls.

3. The light-sensitive photographic material of claim 1 wherein the emulsion is a silver chlorine-silver bromine emulsion which produces upon photographic processing a warm brown image thereon.

4. The light-sensitive photographic material of claim 1 wherein the emulsion layer is on a paper support.

5. A method of producing a photographic image in a photographic material which comprises incorporating in a. silver halide emulsion from 2090% of gelatin modified to have a Van Slyke nitrogen content less than 0.3% so as not to be hardenable by formaldehyde, casting the silver halide emulsion into a supported layer, covering said supported silver halide emulsion layer with a layer of gelatin, hardening the covering layer of gelatin With formaldehyde and supporting the hardened gelatin layer on the emulsion layer, exposing the supported layers to an original to be reproduced, developing the image in the supported silver halide emulsion layer andrapidlydrying the developed photograph on a heat drum dryer.

References Cited UNITED STATES PATENTS 3,575,703 4/1971 Judd 96-94 3,615,626 10/1971 DOSIE 96- -1143 2,525,753 10/1950 Yutzy '96:-11'4.8 2,614,928 10/1952 Yutzy 96--114.8 2,678,079 10/1'956 Russell 96 1143 3,061,436 10/1962 Himmelmann -96 114;8 3,223,528 12/1965 Vrancken; *96'*11'4.8 3,291,611 12/1966 Krajewski '9 6-114.8 3,442,649 5/1969 Rasch J9,6-50 PL 3,507,678 4/1970 Shimezu 96 67 NORMAN G. TORCHIN, Primary Examiner 3' A. T. SURO PICO, Assistant Examiner US. Cl. X.R. 

